Physical purification

Articles

Physical treatment is the first step in wastewater treatment, which uses UV and sedimentation methods, mostly used for industrial and factory wastewater treatment, which contains materials of heavy industrial and harmful materials. Depending on the type of wastewater, there may be fragments of tree leaves, sand and plastic parts in the fluid entering the treatment plant, and the entry of these particles into the wastewater treatment equipment may cause a lot of damage. Therefore, by eliminating these cases, the intensity of pressure on the components of treatment plants can be reduced and the quality of their output can be increased. This method is done with the help of physical processes that include debridement, granulation, sedimentation, filtration and disinfection. Most of these methods are performed before wastewater treatment, which is also called the initial treatment process.
Garbage
The first stage is water treatment, from which 30 to 40% of solids and suspended particles in the water are separated. Garbage collectors are usually made of nets or rod nets. Some points to consider when designing a garbage collector include the flow rate of the effluent, the diameter of the rods, the distance between the rods (coarse spout), the distance between the rods (fine spout), the angle of installation of the spatula, and The hydraulic drop of the traps becomes. There are different types of garbage collection, some of which we will mention. Garbage collectors include Basket Screen, Bar Screen, Mechanical Screen, and Rotary Screen.
Seedling
The sand grains in the treated effluent are made in three stages using the granulation method, and are removed from the water stream. The grain collection unit is divided into three parts, which include the grain collection unit with eddy current, horizontal, and aeration. The importance of granulation in areas such as reducing the odor of wastewater, preventing the growth of primary and secondary sludge, and maintenance and protection of mechanical equipment should be considered.
ته‌شنینی
At this stage, the flow of purifying water, after entering the settling tank, settles the grains with a diameter of more than 10 microns. These precipitated solids, which are sludge, are transferred to the sludge digester through special tools. In designing sedimentation ponds, it is very important to determine the type of particles and the rate of sedimentation. Physical sedimentation is the most widely used operation of a wastewater treatment plant.
Aeration
By adding air to the aeration stage, biodegradation, the growth of microorganisms and, consequently, the loss of organic matter occur. This part can be considered as an integral part of the water treatment process. Self-aeration consists of three groups: central aeration, surface aeration, and submerged aeration. To perform sewage aeration, air diffusers can be used to inject compressed air. These diffusers are also divided into different types of small, medium, and large bubbles.
Aeration diffuser
Diffuser literally means player or publisher. Diffusers or air nozzles are used as a special ventilation tool in the biological reactor of sanitary and industrial wastewater treatment. They are divided into two categories, Fine bubble and Coarse Bubble, in terms of the type and size of bubbles they produce. The smaller the size of the air diffuser bubbles, the faster the ventilation because in this case the outer surface of the bubbles increases and large bubble diffusers are used to create turbulence.
Diffusers are mainly divided into three groups in terms of shape: Disc, Tube and Plate. The type of disc is more popular due to its suitable aeration characteristics and high resistance to clogging and easy installation. . They are produced in three sizes: air diffuser 25 cm, air diffuser 30 cm, air diffuser 35 cm.
Tubular diffusers are usually used in tanks that are small in volume and require high ventilation. They are also used in aeration ponds in the deep aerated activated sludge process, sludge storage ponds, and the SBR and MBR wastewater treatment systems.
The appearance of plate diffusers in particular reduces air pressure and increases the life of the diffuser compared to other types of diffusers. The advantages of this group include the following: They can be used in all conditions, and easy washing, and high oxygen transfer coefficient are also notable features.
The sewage diffuser or membrane diffuser is responsible for injecting the air produced by the blower. Micro-disc bubble diffusers are the best type for aeration. They consist of a polymer body or frame and a flexible rubber membrane made of EPDM or silicone. Plastic membranes have very small holes for air to escape. Ventilation diffusers and membranes are normally connected to a piping system and are pressurized by an air blower. In fact, they disperse the air produced by the blower and have no role in producing the air.
Diffusers are used in the water and wastewater treatment industry, the automotive industry, and fish farming. The greater the depth at which the diffusers are installed (the depth of the pool or pond), the higher the oxygen transfer process.
Filtration
Solid particles that were not removed in the previous steps are separated at this stage by passing through a variety of filters. Some of the equipment in this process includes sand filters (the most common of which), carbon filters, ultrafiltration, and microfiltration. The purpose of this method is to remove suspended water particles that have passed the stage of coagulation, flocculation and sedimentation, and finally clear water with close turbidity.